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Old 05-13-2011, 07:16 AM
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Not sure how I got here.
 
Join Date: Dec 2009
Location: Orange County NY
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Hu- You know there's some funny stuff in yer graphs...... In the "15gp22-21axp22.pdf" that includes "RX43" in the on screen title. The 15gp22 actually has a narrower color spectrum than the 21axp22, and much narrower than p22 phosporous. Smaller triangles on the graph do actually indicate narrower color spectrum. And on the measured graphs both the 15gp, and the 21axp seem to have a very similar shape, except for the brightness level. (You notice in the old RCA p22 graphs also put up on this thread RCA correctly uses the term "relative" in its brightness scale, the vertical left scale. Relative in this case is kind or normalizing with refrence to brightness.) For actual more acurate comparison you are going to have to measure both, or all tubes you compare at very similar brightness levels. (or beam currents, Something I took exception to when this discussion took place many years ago on Pete's private site.) You will get very hard to distinguish readings using those scales with such wide differences in light levels. Think about reading 2V acurately on an analog meter when you chose to use the 400V full scale deflection setting. And you also have to first establish that your instrument has a flat response across the full spectrum. And in addition, that the instrument is accurate across all light intensity levels. And as for the overall screen face color, it may just be the difference in the material between the phosphorous pigment, or in the material used to hold the phosphorous in suspension when deposited on the screen. Anyway just a squirrels thought on the presented data.
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